Spec Clutch SU335 Stage 5 Full-Metallic Clutch Kit with Sintered Iron Disc

The Spec Clutch SU335 Stage 5 Clutch Kit represents the top of SPEC's performance clutch lineup, engineered for drivers who demand maximum torque capacity and aggressive performance. Featuring a sintered iron full-metallic disc with the highest possible friction coefficient, this clutch kit is built for extreme street use, drag racing, pulling, and autocross applications. It is technically street-drivable, but its uncompromising race-oriented design means everyday street manners take a back seat to outright performance.

At the heart of the Stage 5 system is a full-face, unsprung (solid) hub disc secured with a robust 12-rivet assembly. The entire hub and disc assembly is heat-treated for enhanced strength and long-term durability under high-stress, high-heat racing conditions. The high-clamp pressure plate works in tandem with the sintered iron friction material to deliver consistent, repeatable engagement — critical for perfecting drag race launches or managing power under competition conditions.

Key Features:

• Sintered iron full-metallic friction material — highest available friction coefficient for maximum torque transfer
• High-clamp pressure plate for aggressive clamping force beyond OEM levels
• Full-face, solid 12-rivet unsprung hub — heat-treated for strength and durability
• 9-inch disc diameter with 24-spline input shaft interface (0.938 in. input shaft diameter)
• Bearing and tool kit included for straightforward installation
• Torque capacity: 390 ft-lbs
• Sold as a complete kit

Ideal Driving Applications: Extreme Street, Drag Racing, Pulling, Autocross

Note: The solid/unsprung hub design does not absorb drivetrain vibration the way a sprung hub does. Clutch chatter and increased drivetrain harshness are expected characteristics of this race-oriented design. This clutch is best suited for dedicated performance and competition builds.